Rajkummar and Kangana have also worked together in the 2013 film "Queen".
Asked how the bond has evolved between the two actors, Rajkummar told IANS: "We have become way more comfortable with each other than we were earlier because (that time) I did not know her and she did not know me.
"But now it's been about three-four years, we kept meeting in between at different events and parties... So, the comfort level is definitely there."
"Mental Hai Kya" is slated to release on February 22, 2019. It is written by Kanika Dhillon and helmed by National award-winning director Prakash Kovelmudi, who has helmed south Indian films like "Anaganaga O Dheerudu" and "Size Zero".
"Imli" is touted to be a love story which deals with relationships on a very human level. The shooting will begin in November.